Nigrospora oryzae (Berk. & Broome) Petch, J. Indian bot. Soc. 4: 24 (1924)

Index Fungorum number: IF 253729; Facesoffungi number: FoF 06596

Basionym: Monotospora oryzae Berk. & Broome, J. Linn. Soc., Bot. 14: 99 (1873) [1875]                      Khuskia oryzae H.J. Huds., Trans. Br. mycol. Soc. 46(3): 358 (1963)
                     Apiospora oryzae (H.J. Huds.) Arx, Gen. Fungi Sporul. Cult., Edn 2: 129 (1974).

Pathogenic or saprobic on leaves of Scirpus sp. (Cyperaceae). Asexual morph: Hyphae smooth, branched, septate, hyaline or pale brown. Conidiophores reduced to conidiogenous cells. Conidiogenous cells 8.6–14  × 6.4–11.9 μm diam. (x̄ = 11.18 × 7.98 μm, n = 30), aggregated in clusters on hyphae, monoblastic, determinate, ampulliform or doliiform, and hyaline to pale brown. Conidia 9.0–13.2 × 12.6–15.8 μm diam. (x̄ = 10.95 × 14 μm, n = 50), formed abundantly, solitary, globose or oblate, dark brown to black, shiny, smooth, and aseptate. Sexual morph: Undetermined.

Culture characteristics – Colonies on PDA reach 9 cm diam. in 6 d at 25 C, circular, entire margined, floccose, filiform, surface and reverse initially white, becoming dark gray, or black toward the center with age.

Material examined – China, Shandong Peninsula, on living leaves of Scirpus sp., October 7 2017, Yuanyuan Hao (JZBH 3230004), living culture JZB 3230004, and KUMCC 19-0225.

Leaf spot symptoms – Randomly scattered and elliptical-shaped leaf spots are composed of dark brick, slightly dispersed outer halo with light brown inner core, and margined by healthy leaf tissues.

Other materials examined – China, Shandong Peninsula, on living leaves of Phyllostachys nigra (Lodd. ex Lindl.) Munro (Poaceae), October 7 2017, Yuanyuan Hao (JZBH 3230002), living culture JZB 3230002, KUMCC 19-0223; China, Shandong Peninsula, on living leaves of Rudbeckia hirta L. (Asteraceae), October 7 2017, Yuanyuan Hao (JZBH 3230003), living culture JZB 3230003, and KUMCC 19-0224.

Notes – Nigrospora gorlenkoana and N. oryzae are reported to have the same synonym of Basisporium gallarum in Mycobank. However, in our phylogenetic analysis, N. oryzae and N. gorlenkoana are placed in two distinct clades. Khuskia oryzae was introduced as the teleomorph of N. oryzae. The multi-gene phylogeny generated herein indicates that our strains of Nigrospora oryzae form a strongly supported lineage (98% ML, 100% MP, and 1.00 BYPP) in the N. oryzae cluster (Figure 1). Base pair comparison of ITS, TEF, and TUB2 gene regions between our strain (JZB 3230004) and reference strain of N. oryzae (LC 5243) reveals less than 1% difference. The morphological characters, such as conidiogenous cells, conidial dimensions, and culture characteristics, also overlap, confirming that the two strains are the same species. This is the first time N. oryzae has been reported from Scirpus sp., which is an aquatic grass-like plant species, Phyllostachys nigra commonly known as black bamboo and Rudbeckia hirta, a garden plant belongs to the sunflower family.

Figure 1. Multilocus phylogenetic tree based on the combined ITS, TEF, and TUB2 sequences alignment generated from a maximum likelihood phylogenetic analysis. Bootstrap support values for ML, MP (> 70%), and posterior probabilities (> 0.9) are given at the nodes (ML/MP/PP). The tree is rooted with Arthrinium malaysianum (CBS 102053) and Arthrinium obovatum (LC 4940). (* indicates the ex-type isolates).

Figure 3. Nigrospora oryzae (JZB 3230004). (a and b) Appearance of leaf spots on the host substrate; (c and d) Upper view (c) and reverse view (d) of culture on PDA; (e) Surface view of the colony on PDA; (f) Colony on PDA; (g–k) Mature conidia attached to conidiogenous cells. Scale bars f, g = 20 μm, h, i = 10 μm.